Process for the continuous mutual reaction of two liquids of different specific gravities on the counter-current principle



July 28, 1936. K'SCHMID 2,048,820 PROCESS FOR THE CONTINUOUS MUTUAL REACTION OF TWO LIQUIDS OF DIFFERENT SPECIFIC GRAVITIES ON THE COUNTER CURRENT PRINCIPLE 2 Sheets-Sheet 1 Filed Jan. 16, 1935 w mv July 28, 1936. K. SCHMID 2,048,820 PROCESS FOR THE CONTINUOUS MUTUAL REACTION OF TWO LIQUIDS OF DIFFERENT SPECIFIC GRAVITIES ON THE COUNTER CURRENT PRINCIPLE Filed Jan. 16, 1933 2 Sheets-Sheet 2 Patented July 28, 1936 unnan STATES PATENT OFFICE I Claim.

This invention relates'toia processifor thec'ontinuous mutual reaction {of two? "liquids of dit- 'ferent specific gravities on the counter current principle in an apparatus composed of a number of mixers through which now bpth liquids but in opposite directions with respect to one another. Communication betweenrthe mixers is established by one or more pipes ascending. in the direction of flow, the first mixer and the last mixer-being in communication with overflowpipes by means of an ascending pipe. Accordin'g-totliis process, the heavier liquid is mtroduced into the mixer provided With t'he' outlet fof the'lighter-liquid While. the lighter liquidis a'dm-itted; to ther mix er atlthe opposite end of the'a parahs. In view of this novel arrangement of'the ascending communication pipes between the mix'eisiit is possible to fully dispense with separators necessary when working according to' known.=-processes of continuous reaction on the: countercurrent prmciple. In these 'known processes apparstus are employed in' whi'ch mixing compartments are connected in series, however in:- these' known apparatus a separator is arranged behind each mix ing compartment in which-the emulsion separated and thereafter the tw'o liquids are again supplied tothe next mixing compartment on the counter-current principle. in the known processes a separator must; be: provided for every mixing compartment. A thorough-separation of the liquids must take place in the separators, because otherwise the advantage of the counter-current principle is-lost or otherwise diminished. In-the' knowii processesptne size of the separators-must be suited to the speed of separation order to cause-a thorough separation. For instance in the case of washing nitroglycerine, the capacity--ofi'the separator must be suited for a fl'owoi at ieast "three-quarters of an hour, for instance for a yield of "500 kilogrammes nitroglycerine per hour and a washing liquid 'of 500- kilogrammes; the separator -niust have a capacity 017-50 kilogrammes. Now it six mixers are necessary for carrying out} the time ess, the capacity of the separators has to b adaptedto 4500 kilog rammes These drawbacks are aveidcd acedfding: to the present invention by arranging inclined-passages between the mixers in place of separators.

mana ement-the known example above described, in the event of like conditions, it is rendered possible according to the present invention to reduce the capacity of the communication passages between two mixing compartments to approximately 30 kilogrammes. In this case all? the communication. passages together are of a capacity of no more than 180 kilogrammes. This advantage would be still further enhanced in the case of a process in which the separation is carried out still slower.

. With respect tothe solubility of the two liquids it is remarked, that the specifically heavier initial product must be difiicultly soluble or quite insoluble in the specifically lighter final product,

and the specifically lighter initial product must id be difiicultly soluble or quite insoluble the specifically heavier final product.

The apparatus according to the invention is suited for the reaction of two convenient liquids of different specific gravities, such as ior'instance f5 nitro-esters or nitro-products with water'or alkaline solutions for their clarification or neutralization,. benzoL. hydro carbons or other substances with acids for nitration, crude petroleums with acids for refining and the like.

20 Diagrammatic views of the apparatus according. to the present invention are illustratedby way 'of' example in Figs. 1 and 2 of the accom panying drawings, it being supposed that acid nitroglycerine is washed with an alkaline waste 5 which the dots represent the lighter liquid and 3 the dashes indicat'e'the' heavier liquid;

In the drawings, A, B and C designatevessels which are open at the top andin which are' mixed two; liquids of difierent specific gravitiesfor instancexacidinitroglycerine :and alkaline washing liquid.

For carrying out the mixing operation, air is blown through the tubes 1 and into the liquid. If-desired also mechanical agitators, not shown m-the drawings; may be arranged in the vessels. rme vessels A, B' and C' are interconnected by ascending. pipes band 0, while inclinedpipes a and (1, provided with overflow pipese and or respectively are secured to the outer vessels A and respectively. A cock 1 serves for closing or opening-the overflow pipe e.

Before the process is-started, the entire appachargedwith washing liquid up toa p the overil'dw pipeg. Agitation takes place within the vessels and The cock I is shut. Washing liquid is continuously admitted by way of the inlets w or wl and flows uninterruptedly through the apparatus and finally leaves the same by way of the pipe 9. The acid nitroglycerine uninterruptedly enters by way of the inlets or 11.1 and, being the specific heavier liquid, flows through the pipe d and into mixer C. In View of the mixing an emulsion is formed the specific gravities.

in the mixer C and the acidity of the nitroglycerine and of the washing liquid are balanced in accordance with the afiinity of these two liquids with respect to the acid. The speed of theflow through the pipes a, b, c, and d can be controlled by suitably dimensioning the comcending water in the direction towards the mixer 15 B. The separators, which heretofore were arranged in apparatus operating on the countercurrent principle between each pair of mixers, separated water and nitroglycerine according to According to the present invention, a separation of both liquids is not necessary" in view of the arrangement of the communication pipes. The emulsion in the mixer 0 consists of already washed nitroglycerine and acidwater in fine distribution, whereby the ni-'- troglycerine so to say is in suspension in the acid water. Now ifithis emulsion sinks in 'the'communication pipe '0 towards the ascendingfresh water, the acid "from the water-phase of the emulsion coming from the mixer C is washed back into the latter by the fresh water. Drops of nitroglycerinef which may pass intothe mixer B are not separated, but the water surrounding the same does not contain any acid anymore, derived from the water-phase of the mixer C. The nitroglycerine, which has been washed. already, is thoroughly mixed again with fresh or weak alkaline; water and passes in the same way. through the communication pipe b. and into the mixer A';-and from here through the pipe a into s.

The nitroglycerine,is'completely separated from the waterat s and leaves the apparatus by way of the outlet e whenever the cock is opened and if in the pipea a suflicient quantity of. nitroglycerine hasaccumulated, so that at leas'tthe Whole ascending pipe is filled between 6 and 5, whereby .thisf liquid-column of nitroglycerine prevents the discharge of .water through this overflow. The height of the overflow pipe e must be adju'stedin accordance with the specific gravitiesj of both liquids and the now puri- "fied nitroglycerine'fiows out continuously by way washing liquid which may be slightly alkaline are meeting; whereby the latter fully cleans the former; Anyidesired number of mixing vessels A, 3.10 maybe provided. In this way. purified neutral nitroglycerine is obtained with the smallestaquantities; of water and alkali. An excess of alkali, taken in by'the nitroglycerine during the washing process, can be washed out again in the vessel A, because clean water can be charged into the vessel A while alkali is added in the vessel B only. Further it is possible. to introduce or lead off any heat by enclosing the mixing vessels and separation pipes in a heating jacket or in a cooling jacket. Thus in this apparatus any separation of the two liquids according to their specific gravities does not take place between the mixing places, but'practically the same effect can be attained in that the like phases assimilate and force back one another in the communication pipes throughwhich the two liquids mustflow-in opposite directions to each other, because no other way of communication is at disposal. In the illustrated example, the acid from thewater of the emulsion originating in the mixer C iswashed back from the pipe 0 into the mixer Cbyv the ascending fresh water.

' The" assimilation of like phases in emulsions is a-general rule and therefore this is possible in all those cases in which two liquids can be washed, cleaned or enter into reaction on. the counter-currentprinciple. J 'By .bending the communication pipes or by arranging'obstacles, screens or the like within the same it is possible to readily mix both liquids during their passage. in opposite directions through the communication pipes, whereby the assimilation'to the like phases is promoted.

The construction of the mixers does not form a part of thepresent invention and. therefore the same are illustrated diagrammatically in the drawing; The mixing is carried out by air' current or by: propeller, but it must be such that the heavier liquid entering at the bottom is raised and is discharged at. the top. If' the overflow pipee is disposed higher than the overflow pipe 9, the apparatus will be filled .with the heavier liquid and in this event the lighter liquid is forced downward by agitation from" the top-where it enters the mixerrand leaves the same at the bottom outlet. The mixer may be such as is shown and described for instance, in thespecification of U.-S. Patent No...1,893,4l7, dated January 3,

What I'claim is::. I i 1 Process for thecontinuous' mutual'reaction of twomutually insoluble or difiicultly soluble liquids of diiferentspecific gravities on the counter-current principle. in an apparatus comprising interconnectedmixers, which consists in in troducingathe lighter'liquidrat one end and the heavier liquid atthe other end of the apparatus, allowing said liquids to flow continuously but. in opposite directions. througha passageway con necting two adjacent mixers and ascending .in the directionijof fiow of the lighter liquid, where by. the heavier liquid descends through the as-.-

.cending lighter liquid and "washes .backpinto ,the 

